Preoperative factors predicting spontaneous clearance of residual stone fragments after flexible ureteroscopy

Int J Urol. 2015 Apr;22(4):372-7. doi: 10.1111/iju.12690. Epub 2015 Jan 19.

Abstract

Objective: To investigate factors predicting spontaneous clearance of residual renal fragments after flexible ureteroscopy.

Methods: Among 546 patients who underwent lithotripsy with flexible ureteroscopy, 81 had residual renal fragments, as determined by kidney-ureter-bladder films on postoperative day 1. The final outcome was determined at 3 months after the last flexible ureteroscopy session using non-contrast computed tomography. Patient characteristics and preoperative factors were analyzed using the unpaired t-test and χ(2)-test. Correlations between the possible predictive factors and the spontaneous clearance of residual renal fragments after flexible ureteroscopy were analyzed using a multivariate logistic regression model with backward selection.

Results: Non-contrast computed tomography at postoperative month 3 showed that 33 cases (40.7%) had spontaneous clearance of residual renal fragments, whereas 48 (59.3%) showed non-clearance. Significant differences were found between these cases in terms of stone number, stone location, presence of lower pole calculi and preoperative stent placement. Multivariate assessment showed that stone number (P = 0.004), presence of lower pole calculi (P = 0.021) and presence of hydronephrosis (P = 0.024) were independent predictors of the spontaneous clearance of residual renal fragments after flexible ureteroscopy.

Conclusions: Stone number, presence of lower pole calculi and presence of hydronephrosis are independent predictive factors of the spontaneous clearance of residual renal fragments after flexible ureteroscopy.

Keywords: computed tomography; helical; kidney stone; lithotripsy; multivariate analysis; ureteroscopy.

MeSH terms

  • Aged
  • Area Under Curve
  • Female
  • Humans
  • Hydronephrosis / etiology
  • Kidney Calculi / diagnostic imaging
  • Kidney Calculi / pathology*
  • Kidney Calculi / therapy*
  • Kidney Calices
  • Lithotripsy
  • Male
  • Middle Aged
  • Preoperative Care
  • ROC Curve
  • Radiography
  • Remission, Spontaneous
  • Retrospective Studies
  • Stents
  • Treatment Outcome
  • Ureteroscopy